One of the many goals in the information age is to transfer information faster and more efficiently. Information is transmitted through various methods, all with limitations measured in bits/second. The two primary methods adopted for achieving faster and more efficient information transfer are: 1) design equipment that can transfer more bits per second; and 2) design systems that require less bits to carry more information. The present invention is directed at the latter method.
There are many data compression tools currently in existence. The standard feature for most of them is to take common repeating bits of information and “abbreviate” them with predetermined digital “abbreviations” that require fewer bits. The related decompression tool decompresses the compressed data file by “unabbreviating” the predetermined digital “abbreviations” after receiving a key or dictionary of the “abbreviations”. The number of known digital “abbreviations” and/or the number of common repeating bits effectively limits this type of compression tool. Therefore a compression tool is needed that does not rely on common repeating bits or known digital “abbreviations” or can expand the space of abbreviations that can be represented efficiently.
Furthermore, the decompression tool normally must access a key to the “abbreviations”. The key can require a great deal of memory itself. While the memory required is probably not a significant burden on a desktop or laptop computer, if the key is stored on a hard drive, it is a burden for handheld devices. Cellular phones and other portable, handheld devices do not have the hard drive space to efficiently carry or receive an “abbreviations” key. Therefore, a compression tool is needed that does not require an “abbreviations” key or any similar memory burden to decompress a compressed file.
In general, a chaotic system is a dynamical system which has no periodicity and the final state of which depends so sensitively on the system's precise initial state that its time-dependent path is, in effect, long-term seemingly random even though it is deterministic. Identical chaotic systems can be distributed in a secure manner between parties. Parties can then use the chaotic systems for data transmission after synchronizing their chaotic systems.
In one method, described in Short, et al—Method and Apparatus for Secure Digital Chaotic Communication—application Ser. No. 09/436,910 filed Nov. 9, 1999 and incorporated herein by reference (“Short et al.—Chaotic Communication”), a chaotic system is used to generate a secured digital communication link. An encrypting party creates a message bit stream to be transmitted to a decrypting party. Controls are intermittently applied by a transmitter-encoder to a chaotic system corresponding to the message bit stream. A control/no control bitstream is thereby created in which a 0 indicates that no control was applied and a 1 indicates that a control was applied. The control/no control bitstream and a prepended synchronization bitstream are transmitted to a receiver-decoder. An identical chaotic system in the receiver-decoder is driven into synchrony and is then subject to intermittent controls based on the control/no control bitstream, thereby causing the identical chaotic system to generate the message bit stream. It would be useful to harness the attributes of chaotic systems used for the secured digital communication link for data compression as well.